1. Field
Embodiments relate to a walking robot which simultaneously produces a map corresponding to a space about which the robot moves and estimates the position of the robot using image data captured by cameras, and a simultaneous localization and mapping method thereof.
2. Description of the Related Art
In general, walking robots refer to robots which move using two or more legs in the same manner as animals or humans. These walking robots pass over obstacles unlike wheeled robots, and particularly, bipedal walking robots are favorable when working in the same living space as humans due to the external appearance thereof being similar to humans and are regarded as the key technology of humanoid robots due to the external appearance thereof without repulsing humans.
In order to enable a walking robot to plan a path to a desired destination within a space about which the robot moves and to autonomously walk, it needs to be assumed that the walking robot recognizes the position thereof within an indoor space in real time.
As one method to recognize the position of a walking robot, artificial landmarks are used. Through such a method, specific artificial landmarks distinguished from the background of a space about which the walking robot moves are installed in advance and are recognized using position sensors, such as vision sensors (cameras) or ultrasonic sensors mounted on the walking robot, thereby enabling the walking robot to recognize the current position thereof. The walking robot, which has position (coordinate) data of the artificial landmarks with respect to the coordinates of an origin in advance, measures relative positions of the walking robot with respect to the artificial landmarks, thus measuring a current position of the walking robot with respect to the coordinates of the origin. Through such a position recognizing method using artificial landmarks, if the landmarks are successfully detected, absolute position data are obtained, but if detection of the landmarks fails due to shielding of the landmarks, position data are not obtained and when the size of a space about which a positioning system will be built is increased, a burden due to installation of the landmarks is increased. Further, in order to apply the position recognizing method using artificial landmarks, constraint in that the walking robot recognizes position (coordinate) data of the artificial landmarks present within a space about which the walking robot moves in advance is required.
As another method to recognize the position of a walking robot, natural landmarks are used. Through such a method, additional artificial landmarks are not installed in a space about which the walking robot moves, and peculiar objects in an environment are used as landmarks to recognize a current position of the walking robot. As one representative example of the above method, there is simultaneous localization and mapping (SLAM) technology. The SLAM technology refers to technology in which peripheral environmental data of a walking robot are detected and the detected data are processed to simultaneously produce a map corresponding to a space (work operable space) about which the walking robot moves and estimate the absolute position of the walking robot. Recently, research into image-based SLAM technology in which vision sensors (cameras) are mounted on a main body of a waking robot and SLAM is achieved using image data captured by the cameras is underway. The walking robot simultaneously estimates position data of the walking robot and position data of landmarks using feature points extracted from the image data, captured by the cameras, as the natural landmarks. However, the walking robot has great rectilinear/rotary movement and vibration in a three-dimensional direction during walking, and such movement and vibration function as disturbances of the cameras and thus influence the image data captured by the cameras. Therefore, accurate estimation of the position of the walking robot using only the image data captured by the cameras is substantially difficult, and thus research into measures to overcome such a problem is underway.